Acid Sulfate Soil Materials

The following nomenclature and definitions used for acid sulfate soil materials is as defined by the 2nd edition of Australian Soil Classification (Isbell and National Committee on Soils & Terrain 2016):

Sulfidic Material

Hypersulfidic material: Sulfidic material that had a field pH of 4 or more and the pH dropped by at least 0.5 units to less than 4 when incubated at field capacity for at least 8 weeks.

Hyposulfidic material: Sulfidic soil material that had a field pH of 4 or more and the pH dropped by at least 0.5 units to not less than 4 when incubated at field capacity for at least 8 weeks.

Sulfuric Material

Soil material that has a pH < 4 (1:1 by weight in water, or in a minimum of water to permit measurement) when measured as a result of the oxidation of sulfidic materials and evidence of sulfidic material such as underlying sulfidic material and/or the presence of yellow masses of jarosite along old root channels and faces of peds.

Monosulfidic

Soil material containing ≥0.01% acid volatile sulfide.

 Isbell, R. F., National Committee on Soils and Terrain, 2016. The Australian Soil Classification, Second Edition. CSIRO Publishing, Clayton, Victoria, Australia